Notes on Mesozoic vertebrate fossils / by O.C. Marsh.

  • Othniel Charles Marsh
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: Notes on Mesozoic vertebrate fossils / by O.C. Marsh. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    9/20 page 175
    TJie wear is in front of the apex, and on one side, sometimes on both sides, as in figure 6, Plate III. This tooth may be taken as the type of a new species, AuUysodon cristatus. The fact that these peculiar teeth are apparently in pairs, and are in themselves more like the teeth of mammals than of reptiles, has long been considered by the writer an argu- ment for the mammalian character of the smaller forms at least. Tiie large crenulated teeth described by Leidy strongly resemble those of carnivorous Dinosaurs, as he con- sidered them, but uo Dinosaur teeth of this form have been found in position in the jaws. The next smaller size, with very faint crenulations, one of which is figured in Flate HI, figure 5, is too large for any mammal yet known from the Laramie, and this is true, also, of those figured by Leidy. Many of the smaller teeth of this ty|)e, if considered a])art from the others, would naturally be regarded as mamnuilian incisors, especially from the lower jaw, and the wear of the suuimits would in itself tend to strengthen this reference, if some of these teeth aloue were considered. A number have been found, however, that show wear not only on the summit and on one side near the summit, but also on the other edge. This would im])ly, if these teeth are really lower incisors, either that the rami of the lower jaw were so loosely united at the symphysis that motion between them was possible, so that the incisors could thus rub against each other, or that these teeth were separated so as to admit the upper opposing teeth between them. That some of these teeth are nuimmalian incisors there can be but little doubt, and this doubt can only be removed entirely by the fortunate discovery of a tooth in position in the jaw. Vimolopterj/x^ Marsh, 1889. The only bird hitherto known from the Laramie deposits is Cimolopteryx varus, the type specimen of which is rej)resented on Plate III, figure 2. Ai'iother species, about twice the size of the first,^ is indicated by various remains, among tliem the cora- coid. This bone lacks the strong inner [)rocess near the pit for the scapula, which is characteristic of the smaller form. The in-esent species, which may be called Cimolopteryx rettmis, is also from Wyoming. The new Laramie fossils here described and figured were collected by Mr. J. B. Hatcher and party, in the Ceratops beds of Montana and Wyoming. They will all be discussed more fully in another communication. New Haveu, Conu., July 18, 1892.
    digitised image 1
    digitised image 2
    digitised image 3